Device and method for treatment of mitral insufficiency

ABSTRACT

A device for treatment of mitral annulus dilatation comprises an elongate body having two states. In a first of these states the elongate body is insertable into the coronary sinus and has a shape adapting to the shape of the coronary sinus. When positioned in the coronary sinus, the elongate body is transferable to the second state assuming a reduced radius of curvature, whereby the radius of curvature of the coronary sinus and the radius of curvature as well as the circumference of the mitral annulus is reduced.

REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 10/953,047, filed Sep. 29, 2004, now U.S. Pat. No. 7,311,728which is a continuation of U.S. patent application Ser. No. 10/019,563,filed Jul. 1, 2002, now U.S. Pat. No. 7,044,967, which is a nationalstage under 35 U.S.C. §371 of international application PCT/SE00/01369,filed Jun. 28, 2000 which designated the United States, and whichinternational application was published under PCT Article 21(2) in theEnglish language and which claims priority to SE 9902455-6, filed Jun.29, 1999, the disclosures of which are incorporated fully herein byreference.

FIELD OF THE INVENTION

The present invention generally relates to a device and a method fortreatment of mitral insufficiency and, more specifically, for treatmentof dilatation of the mitral annulus.

BACKGROUND

Mitral insufficiency can result from several causes, such as ischemicdisease, degenerative disease of the mitral apparatus, rheumatic fever,endocarditis, congenital heart disease and cardiomyopathy. The fourmajor structural components of the mitral valve are the annulus, the twoleaflets, the chordae and the papillary muscles. Any one or all of thesein different combinations may be injured and create insufficiency.Annular dilatation is a major component in the pathology of mitralinsufficiency regardless of cause. Moreover, many patients have a mitralinsufficiency primarily or only due to posterior annular dilatation,since the annulus of the anterior leaflet does not dilatate because itis anchored to the fibrous skeleton of the base of the heart.

Studies of the natural history of mitral insufficiency have found thattotally asymptomatic patients with severe mitral insufficiency usuallyprogress to severe disability within five years. At present thetreatment consists of either mitral valve replacements or repair, bothmethods requiring open heart surgery. Replacement can be performed witheither mechanical or biological valves.

The mechanical valve carries the risk of thromboembolism and requiresanticoagulation, with all its potential hazards, whereas biologicalprostheses suffer from limited durability. Another hazard withreplacement is the risk of endocarditis. These risks and other valverelated complications are greatly diminished with valve repair.

Mitral valve repair is theoretically possible if an essentially normalanterior leaflet is present. The basic four techniques of repair includethe use of an annuloplasty ring, quadrangular segmental resection ofdiseased posterior leaflet, shortening of elongated chordae, andtransposition of posterior leaflet chordae to the anterior leaflet.

Annuloplasty rings are needed to achieve a durable reduction of theannular dilatation. All the common rings are sutured along the posteriormitral leaflet adjacent to the mitral annulus in the left atrium. TheDuran ring encircles the valve completely, whereas the others are opentowards the anterior leaflet. The ring can either be rigid, like theoriginal Carpentier ring, or flexible but non-elastic, like the Duranring or the Cosgrove-Edwards ring.

Effective treatment of mitral insufficiency currently requiresopen-heart surgery, by the use of total cardiopulmonary by-pass, aorticcross-clamping and cardioplegic arrest.

To certain groups of patient, this is particular hazardous. Elderlypatients, patients with a poor left ventricular function, renal disease,severe calcification of the aorta, previous cardiac surgery or otherconcomitant diseases, would in particular most likely benefit from aless invasive approach, even if repair is not complete. The currenttrend towards less invasive coronary artery surgery, withoutcardiopulmonary by-pass, as well as PTCA will also call for adevelopment of a less invasive method for repair of the oftenconcomitant mitral insufficiency.

SUMMARY

A first object of the present invention is to provide a device and amethod for treatment of mitral insufficiency without the need forcardiopulmonary by-pass and opening of the chest and heart.

A second object of the invention is to provide reduction of the mitralannulus using less invasive surgery.

According to the present invention, a device for treatment of mitralisinsufficiency comprises an elongate body having such dimensions as to beinsertable into the coronary sinus and having two states, in a firststate of which the elongate body has a shape that is adaptable to theshape of the coronary sinus, and to the second state of which theelongate body is transferable from the said first state assuming areduced radius of curvature, whereby the radius of curvature of thecoronary sinus is reduced as well as the circumference of the mitralvalve annulus, when the elongate body is positioned in the coronarysinus.

Preferably, means are provided for the transfer of the elongate body tothe second state by bending and/or shortening it from a larger radius ofcurvature to a smaller radius of curvature.

The transfer means may comprise-means for bending and/or shortening theelongate body by a preferably asymmetric contraction thereof.

Further, the elongate body may comprise a memory material providing thetransfer to the second state.

In a preferred embodiment, the elongate body may comprise a stent. In analternative embodiment, the device according to the invention maycomprise several stent sections and said bending and/or shortening meansmay comprise wires for shortening the distance between the stentsections.

According to a second aspect, a method of reducing the circumference ofthe mitral valve annulus comprises the steps of inserting an elongatebody into the coronary sinus in the vicinity of the posterior leaflet ofthe mitral valve, and then providing a bending and/or shortening of theelongate body when positioned in the coronary sinus so as to reduce thecurvature of the coronary sinus and thereby reduce the circumference ofthe mitral valve annulus.

Thus, the present invention takes advantage of the position of thecoronary sinus being close to the mitral annulus. This makes repairpossible by the use of current catheter-guided techniques.

The coronary veins drain blood from the myocardium to the right atrium.The smaller veins drain blood directly into the atrial cavity, and thelarger veins accompany the major arteries and run into the coronarysinus which substantially encircles the mitral orifice and annulus. Itruns in the posterior atrioventricular groove, lying in the fatty tissuebetween the left atrial wall and the ventricular myocardium, beforedraining into the right atrium between the atrial septum and thepost-Eustachian sinus.

In an adult, the course of the coronary sinus may approach within 5-15mm of the medial attachment of the posterior leaflet of the mitralvalve. Preliminary measurements performed at autopsies of adults ofnormal weight show similar results, with a distance of 5.3±0.6 mm at themedial attachment and about 10 mm at the lateral aspect of the posteriorleaflet. The circumference of the coronary sinus was 18.3±2.9 mm at itsostium (giving a diameter of the posterior leaflet of 5.8±0.9 mm) and9.7±0.6 mm along the lateral aspect of the posterior leaflet(corresponding to a diameter of 3.1±0.2 mm).

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood by the following description ofpreferred embodiments referring to the appended drawings, in which

FIG. 1 is a cross-sectional view of a part of a heart,

FIGS. 2 and 3 are schematic views of a first embodiment of a deviceaccording to the present invention,

FIGS. 4-6 are schematic views illustrating an instrument, which may beused when positioning the device shown in FIGS. 2 and 3 in the coronarysinus,

FIG. 7 is a partial, enlarged view of the first embodiment shown in FIG.2.

FIGS. 8 and 9 are schematic views illustrating the positioning of thedevice of FIGS. 2 and 3 in the coronary sinus,

FIGS. 10 and 11 are schematic views illustrating the positioning of asecond embodiment of the device according to the present invention inthe coronary sinus, and

FIGS. 12 and 13 are schematic views illustrating the positioning of athird embodiment of the device according to the present invention in thecoronary sinus.

DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view through the heart area of the posterioratrioventricular groove 1, which is filled with fatty tissue. It showsthe posterior leaflet 2 of the mitral valve and the adjoining parts 3, 4of the atrial myocardium and the ventricular myocardium. The coronarysinus 5 is shown close to the mitral annulus 6 and behind the attachment7 of the posterior leaflet 2. Since the coronary sinus 5 substantiallyencircles the mitral annulus 6, a reduction of the radius of curvatureof the bent coronary sinus 5 also will result in a diameter andcircumference reduction of the mitral annulus 6.

The device of FIG. 2 comprises an elongate body 8 made of memory metal,e.g. Nitinol, or other similar material which has a memory of anoriginal shape, illustrated in FIG. 3, and can be temporary forced intoanother shape, illustrated in FIG. 2. This elongate body 8 comprisesone, two or more memory metal strings 9 of helical or other shape so asto fit together and be able of permitting the movements described below.Along the elongate body 8 several hooks 10 are fastened so as to extendradially out therefrom. These hooks 10 are covered by a cover sheet 11in FIG. 2.

The elongate body 8 is forced into a stretched or extended state bymeans of a stabilizing instrument 12 shown in FIG. 4. This instrument 12has two arms 13 at a distal end 14 of a rod 15 and a locking means 16 ata proximal end of the rod 15. The distance between the ends of the rod15 corresponds to the desired length of the elongate body 8 when beinginserted into the coronary sinus 5.

The arms 13 are free to move between the position shown in FIG. 4 and aposition in alignment with the rod 15, as shown in FIG. 6. The lockingmeans 16 has two locking knobs 17, which are pressed radially outwardsfrom the rod 15 by two spring blades 18. Thus, the elongated body 8 canbe pushed over the rod 15 of the stabilizing instrument 12, thenstretched between the arms 13 and the knobs 17, and finally locked inits stretched state on the stabilizing instrument 12 between the arms 13and the knobs 17, as illustrated in FIG. 5.

The rod 15 may be a metal wire which is relatively stiff between thedistal end 14 and the locking means 16 but still so bendable that itwill follow the shape of the coronary sinus 5. Proximally of the lockingmeans 16 the metal wire of the stabilizing instrument 11 is more pliableto be able to easily follow the bends of the veins.

The above-described elongate body 8 is positioned in the coronary sinus5 in the following way:

An introduction sheet (not shown) of synthetic material may be used toget access to the venous system. Having reached access to the venoussystem, a long guiding wire (not shown) of metal is advanced through theintroduction sheet and via the venous system to the coronary sinus 5.This guiding wire is provided with X-ray distance markers so that theposition of the guiding wire in the coronary sinus 5 may be monitored.

The elongate body 8 is locked onto the stabilizing instrument 12, asshown in FIG. 5, and introduced into the long cover sheet 11 ofsynthetic material. This aggregate is then pushed through theintroduction sheet and the venous system to the coronary sinus 5 ridingon the guiding wire. After exact positioning of the elongate body 8 inthe coronary sinus 5, as illustrated in FIG. 8 where the mitral valve 19is shown having a central gap 20, the cover sheet 11 is retractedexposing the elongate body 8 within the coronary sinus 5. This maneuverallows the hooks 10 on the elongate body 8 to dig into the walls of thecoronary sinus 5 and into the heart. The elongate body 8 is still lockedon to the stabilizing instrument 12 such that the hooks 10 engage thewalls of the coronary sinus 5 in the stretched or extended state of theelongate body 8.

A catheter 21, shown in FIG. 6, is pushed forward on the guiding wireand the rod 15 for releasing the elongate body 8 from the locking means16 by pressing the spring blades 18 towards the rod 15. This movementreleases the knobs 17 as well as the arms 13 from engagement with theelongate body 8 which contracts as illustrated in FIG. 9 and as a resultbends towards the mitral valve annulus 6 moving the posterior pairthereof forward (shown by arrows in FIG. 9). This movement reduces thecircumference of the mitral valve annulus 6 and thereby closes thecentral gap 20.

FIG. 7 illustrates a part of an arrangement of the wires 9 and the hooks10 along a peripheral part of the elongate body 8, whereby the elongatebody 8 will be asymmetrically contracted resulting in a bending thereofwhen interconnecting parts 22 of at least some of the hooks 10 areshortened to an original shape.

FIGS. 10 and 11 illustrate an alternative embodiment of an elongate body8′, which is a solid wire in the shape of an open U-shaped ring thatwill engage the wall of the coronary sinus 5 most adjacent to the mitralvalve annulus 6 when inserted into the coronary sinus 5. The elongatebody 8′ consists of a memory metal material which when reverting to itsoriginal shape will bend as illustrated in FIG. 11. The return of theopen ring 8′ to its original shape may be initiated in several ways, asis obvious to the man skilled in the art.

The third embodiment of the elongate body 8″, illustrated in FIGS. 12and 13, comprises three stent sections 23-25 positioned at one end ofthe elongate body 8″, at the middle thereof and at the other end of theelongate body 8″, respectively. These stent sections 23-25 may bepositioned in the coronary sinus 5 as illustrated by conventional means,such that their positions are fixed. They are connected by wires 26, 27,which may be maneuvered from outside the vein system such that thedistances between the adjacent stent sections 23, 24 and 24, 25 arereduced. More specifically, these distances are reduced asymmetrically,i.e. more on the side of coronary sinus 5 most adjacent to the posteriorpart of the mitral valve annulus 6. Thereby, the elongate body 8″ isbent, as illustrated in FIG. 13, and presses the coronary sinus 5against the mitral valve annulus 6 closing the gap 20. Each of the wires26, 27 may thus be viewed as an example or species of a “formingelement,” in that the wires are attached to the elongate body in such away that the elongate body can be manipulated or formed from a first,(in this example) relatively more straight configuration to a second,(in this example) relatively more bent configuration.

Concludingly, the present invention provides a device placed in thecoronary sinus, designed to reduce the dilatation of the mitral annulus.This device is at a distance from the attachment of the posteriorleaflet that does not much exceed the distance at which presentannuloplasty rings are placed by open surgery techniques, and thecoronary sinus is along its entire course large enough to hold such adevice. The device could be positioned by catheter technique or anyother adequate technique and offers a safer alternative to the currentopen surgery methods. The device could be designed or heparin-coated soas to avoid thrombosis in the coronary sinus, thus reducing the need foraspirin, ticlopedine or anticoagulant therapy.

It is to be understood that modifications of the above-described deviceand method can be made by people skilled in the art without departingfrom the spirit and scope of the invention.

1. A medical apparatus for remodeling a mitral valve annulus,comprising: an elongate body having a proximal end region and a distalend region, the elongate body having a first configuration for deliveryvia a catheter to a location adjacent a mitral valve annulus, theelongate body having a second configuration for reshaping the mitralvalve annulus to improve coaption of the mitral valve leaflets; and aforming element attached to the elongate body for manipulating theelongate body from the first configuration to the second configuration;wherein the proximal and distal end regions of the elongate body areconfigured to be anchored to opposing regions of tissue adjacent themitral valve annulus and wherein the elongate body urges the opposingregions of tissue together when manipulated to the second configuration.2. The medical apparatus of claim 1, wherein the forming element isconnected to the elongate body at a point of attachment and the formingelement is movable relative to the elongate body in order to adjust theelongate body between the first and second configurations.
 3. Themedical apparatus of claim 2, wherein the forming element is configuredto be maneuvered from outside the vein system for adjusting the elongatebody.
 4. The medical apparatus of claim 1, wherein the elongate body issized for advancement at least partially into a coronary sinus.
 5. Themedical apparatus of claim 1, further comprising a coating on theelongate body for avoiding thrombosis.
 6. The medical apparatus of claim1, wherein the apparatus is movable from the first configuration to thesecond configuration in response to proximal retraction of the formingelement.
 7. The medical apparatus of claim 1, wherein the apparatus ismovable from the first configuration to the second configuration inresponse to distal movement of the forming element.
 8. The medicalapparatus of claim 1, further comprising a first stent along theproximal end region of the elongate body and a second stent along thedistal end region of the elongate body.
 9. The medical apparatus ofclaim 8, wherein the first and second stents are expandable for engaginga vessel wall.
 10. The medical apparatus as in claim 8, wherein theforming element is coupled to the proximal end region of the elongatebody.
 11. A medical apparatus for remodeling a mitral valve annulus,comprising: an elongate body having a first anchor and a second anchor,the elongate body having a first configuration for delivery through acatheter and a second configuration for reshaping the mitral valveannulus to improve coaption of the mitral valve leaflets; wherein thefirst and second anchors of the elongate body are configured to be fixedto opposing regions of tissue adjacent the mitral valve annulus andwherein the elongate body urges the opposing regions of tissue togetherwhen in the second configuration.
 12. The medical apparatus of claim 11,wherein the first and second anchors include tissue penetrating members.13. A medical apparatus for remodeling a mitral valve annulus,comprising an elongate body having a substantially fixed length, theelongate body being sized for insertion at least partially into acoronary sinus, wherein the elongate body is configured to changecurvature after insertion into the coronary sinus for exerting acompressive force on the mitral valve annulus.
 14. The medical apparatusof claim 11, wherein the elongate body comprises a generally U-shapedmember formed of a resilient material.